CN116965103A - Initial channel access in unlicensed spectrum by directional sensing and communication - Google Patents

Abstract

A method for operating a User Equipment (UE) in a wireless communication system, comprising: the UE decodes a Master Information Block (MIB) or a System Information Block (SIB) or both MIB and SIB received from the base station; determining that a Discovery Burst Transmission Window (DBTW) is enabled based at least on the decoded MIB or SIB; decoding the DBTW parameters; and performing a Random Access Channel (RACH) procedure according to the decoded DBTW parameter.

Description

Initial channel access in unlicensed spectrum by directional sensing and communication

Priority claims and cross-references

This patent application claims priority from U.S. provisional application No. 63/170,974, entitled "Initial Channel Access in Unlicensed Spectrum with Directional Sensing and Communication," filed on 5, 4, 2021, the entire contents of which are hereby incorporated by reference as if reproduced.

Technical Field

The present invention relates generally to systems and methods for digital communications and, in particular embodiments, to techniques and mechanisms for initial channel access through directional sensing and communications.

Background

Channel access in the shared spectrum (unlicensed band) of 57GHz to 71GHz in the European Union (EU) is specified in the european telecommunications standards institute (telecommunications standards institute, ETSI) standard. The standard limits the power spectral density transmission (EIRP) to 23dBm/MHz and the total maximum power (EIRP) to 40dBm. To facilitate coexistence in this portion of spectrum, specifications mandate listen before talk (listen before talk, LBT) procedures.

Licensed exempt spectrum, also known as unlicensed spectrum or shared spectrum, has attracted considerable interest to cellular operators. Long term evolution licensed assisted access (long termevolution licensed assisted access, LTE-LAA) is specified in 3GPP LTE releases 13 and 14. Recently, in new air interface unlicensed (new radio unlicensed, NR-U), operations in unlicensed spectrum (shared spectrum) have been specified in release 16 of the 3GPP new air interface (NR) (3 GPP TS 38.213, the entire contents of which are hereby incorporated by reference).

3GPP and IEEE technologies operating in unlicensed spectrum use listen before talk (listen before talk, LBT) channel access. In some areas, such as the European Union (EU) and japan, LBT rules are enforced by spectrum regulatory authorities to reduce interference risk and provide a more fair coexistence mechanism. The LBT mechanism requires the transmitter to check whether there are other occupants of the channel before transmitting and defer transmission if the channel is occupied.

The present disclosure defines an initial access procedure for directional beam sensing and communication that allows a UE to perform initial channel access to communicate in unlicensed frequency bands in multiple spatial directions required for reasons such as robustness, spatial diversity, multi-TRP and multi-link connections, use of directional sensing and directional communication.

Disclosure of Invention

According to one embodiment, a method for operating a User Equipment (UE) is provided. The method comprises the following steps: the UE decodes a master information block (master information block, MIB) or a system information block (systeminformation block, SIB) or both MIB and SIB received from the base station; determining that a discovery burst transmission window (discovery burst transmission window, DBTW) is enabled based at least on the decoded MIB or SIB; decoding the DBTW parameters; and performing a random access channel (random access channel, RACH) procedure according to the decoded DBTW parameters.

Optionally, in any of the above aspects, the method for operating a UE further comprises: in response to the DBTW being enabled, determining that no DBTW parameter is provided; and in response to determining that the DBTW parameters are not provided, performing a RACH procedure according to the default DBTW parameters.

Optionally, in any of the above aspects, the method for operating a UE further comprises: determining that the DBTW has signal quality reporting; the synchronization signal physical broadcast channel/channel state information reference signal (synchronization signal physical broadcast channel/channel state information reference signal, SSB/CSI-RS) quality is reported.

Optionally, in any of the above aspects, in response to determining that DBTW is not enabled, the UE performs RACH procedure according to no DBTW.

According to another embodiment, a method for operating a User Equipment (UE) is provided. The method comprises the following steps: decoding a master information block (master information block, MIB) or a system information block (systeminformation block, SIB) or both MIB and SIB received from a base station; determining that the listen before talk (listen before talk, LBT) configuration is a default LBT cell configuration based at least on the decoded MIB or SIB; and in response to determining that the LBT configuration is a default LBT cell configuration, sending a message using a directed LBT procedure.

Optionally, in any of the above aspects, the method for operating a UE further comprises: determining that the LBT configuration is not a default LBT cell configuration; and transmitting the message using a directed LBT procedure at least according to the decoded MIB or SIB.

Optionally, in any of the above aspects, the UE transmits the message without performing an LBT procedure.

Optionally, in any of the above aspects, the method for operating a UE further comprises: receiving a message from a base station; detecting a change in LBT; and transmitting the second message using the directed LBT procedure according to the changed LBT.

Optionally, in any of the above aspects, the method for operating a UE further comprises: receiving a message from a base station; determining that LBT has not changed; and transmitting the second message using a directed LBT procedure at least according to the decoded MIB or SIB.

According to yet another embodiment, a method for operating a User Equipment (UE) is provided. The method comprises the following steps: decoding a master information block (master information block, MIB) or a system information block (systeminformation block, SIB) or both MIB and SIB received from a base station; determining that the listen before talk (listen before talk, LBT) configuration is a default LBT configuration based at least on the decoded MIB or SIB; and in response to determining that the LBT configuration is a default LBT configuration, sending a message using a directed LBT procedure.

Optionally, in any of the above aspects, the method for operating a UE further comprises: determining that the LBT configuration is not a default LBT configuration; and transmitting the message using a directed LBT procedure at least according to the decoded MIB or SIB.

Optionally, in any of the above aspects, the method for operating a UE further comprises: determining that the LBT configuration is not a default LBT configuration; and transmitting the message without using any LBT procedure.

Optionally, in any of the above aspects, the method for operating a UE further comprises: receiving a message from a base station; determining that the message LBT is a short signal; and transmitting a third message according to the back-off type LBT in response to a timer timeout of the short signal.

Optionally, in any of the above aspects, the method for operating a UE further comprises: determining that the message LBT is not a short signal; and transmitting the third message according to the LBT configuration.

Optionally, in any of the above aspects, the method for operating a UE further comprises: receiving a message from a base station; determining that the message LBT is a short signal; and in response to determining that the timer of the short signal has not timed out, transmitting a third message without any LBT.

According to yet another embodiment, a method for operating a User Equipment (UE) is provided. The method comprises the following steps: identifying a plurality of synchronization signal/physical broadcast channel (synchronization signal/physical broadcast channel, SS/PBCH) and channel state information reference signal (channel state information reference signal, CSI-RS) directions in accordance with the multi-directional initial access being enabled; performing a listen before talk (listen before talk, LBT) procedure in multiple directions; and transmitting, by the UE, a first message in a plurality of directions, wherein each preamble in the first message corresponds to at least an SS/PBCH block (SSB) or CSI-RS.

Optionally, in any of the above aspects, the method for operating a UE further comprises: receiving a plurality of second messages from the base station in response to the transmission of the first messages; in response to receiving the plurality of second messages, performing a directed LBT procedure; and transmitting one or more third messages, wherein the UE identifies itself as the sole sender of the first message.

Optionally, in any of the above aspects, the method for operating a UE further comprises: receiving one or more fourth messages from the base station in response to the transmission of the one or more third messages; and transmitting a hybrid automatic repeat request/acknowledgement (hybrid automatic repeat request/HARQ/ACK) to the base station, the HARQ/ACK indicating a mapping of the fourth message successfully received by the UE.

According to yet another embodiment, a User Equipment (UE) is provided. The UE comprises: a non-transitory memory including instructions; one or more processors in communication with the memory, the one or more processors executing instructions to: decoding a master information block (master information block, MIB) or a system information block (systeminformation block, SIB) or both MIB and SIB received from a base station; determining that a discovery burst transmission window (discovery burst transmission window, DBTW) is enabled based at least on the decoded MIB or SIB; decoding the DBTW parameters; and performing a random access channel (random access channel, RACH) procedure according to the decoded DBTW parameters.

Optionally, in any of the above aspects, the one or more processors further execute instructions to: in response to the DBTW being enabled, determining that no DBTW parameter is provided; and in response to determining that the DBTW parameters are not provided, performing a RACH procedure according to the default DBTW parameters.

Optionally, in any of the above aspects, the one or more processors further execute instructions to: determining that the DBTW has signal quality reporting; the SS physical broadcast channel/channel state information reference signal (SS physical broadcast channel/channel state information reference signal, SSB/CSI-RS) quality is reported.

Optionally, in any of the above aspects, the one or more processors further execute instructions to: in response to determining that DBTW is not enabled, the RACH procedure is performed according to no DBTW.

According to yet another embodiment, a User Equipment (UE) is provided. The UE comprises: a non-transitory memory including instructions; one or more processors in communication with the memory, the one or more processors executing instructions to: decoding a master information block (master information block, MIB) or a system information block (systeminformation block, SIB) or both MIB and SIB received from a base station; determining that the listen before talk (listen before talk, LBT) configuration is a default LBT cell configuration based at least on the decoded MIB or SIB; and in response to determining that the LBT configuration is a default LBT cell configuration, sending a message using a directed LBT procedure.

Optionally, in any of the above aspects, the one or more processors further execute instructions to: determining that the LBT configuration is not a default LBT cell configuration; the message is sent using a directed LBT procedure based at least on the decoded MIB or SIB.

Optionally, in any of the above aspects, the one or more processors further execute instructions to send the message without performing an LBT procedure.

Optionally, in any of the above aspects, the one or more processors further execute instructions to: receiving a message from a base station; detecting a change in LBT; and transmitting the second message using the directed LBT procedure according to the changed LBT.

Optionally, in any of the above aspects, the one or more processors further execute instructions to: receiving a message from a base station; determining that LBT has not changed; and transmitting the second message using a directed LBT procedure at least according to the decoded MIB or SIB.

According to yet another embodiment, a User Equipment (UE) is provided. The UE comprises: a non-transitory memory including instructions; one or more processors in communication with the memory, the one or more processors executing instructions to: decoding a master information block (master information block, MIB) or a system information block (systeminformation block, SIB) or both MIB and SIB received from a base station; determining that the listen before talk (listen before talk, LBT) configuration is a default LBT configuration based at least on the decoded MIB or SIB; in response to determining that the LBT configuration is the default LBT configuration, a message is sent using a directional LBT procedure.

Optionally, in any of the above aspects, the one or more processors further execute instructions to: determining that the LBT configuration is not a default LBT configuration; and transmitting the message using a directed LBT procedure at least according to the decoded MIB or SIB.

Optionally, in any of the above aspects, the one or more processors further execute instructions to: determining that the LBT configuration is not a default LBT configuration; and transmitting the message without using any LBT procedure.

Optionally, in any of the above aspects, the one or more processors further execute instructions to: receiving a message from a base station; determining that the message LBT is a short signal; and transmitting a third message according to the back-off type LBT in response to a timer timeout of the short signal.

Optionally, in any of the above aspects, the one or more processors further execute instructions to: determining that the message LBT is not a short signal; and transmitting the third message according to the LBT configuration.

Optionally, in any of the above aspects, the one or more processors further execute instructions to: receiving a message from a base station; determining that the message LBT is a short signal; and in response to determining that the timer of the short signal has not timed out, transmitting a third message without any LBT.

According to yet another embodiment, a User Equipment (UE) is provided. The UE comprises: a non-transitory memory including instructions; one or more processors in communication with the memory, the one or more processors executing instructions to: identifying a plurality of synchronization signal/physical broadcast channel (synchronization signal/physical broadcast channel, SS/PBCH) and channel state information reference signal (channel state information reference signal, CSI-RS) directions in accordance with the multi-directional initial access being enabled; performing a listen before talk (listen before talk, LBT) procedure in multiple directions; the first message is transmitted in a plurality of directions, wherein each preamble in the first message corresponds to at least an SS/PBCH block (SSB) or CSI-RS.

Optionally, in any of the above aspects, the one or more processors further execute instructions to: receiving a plurality of second messages from the base station in response to the transmission of the first messages; in response to receiving the plurality of second messages, performing a directed LBT procedure; and transmitting one or more third messages, wherein the UE identifies itself as the sole sender of the first message.

Optionally, in any of the above aspects, the one or more processors further execute instructions to: receiving one or more fourth messages from the base station in response to the transmission of the one or more third messages; and transmitting a hybrid automatic repeat request/acknowledgement (hybrid automatic repeat request/HARQ/ACK) to the base station, the HARQ/ACK indicating a mapping of the fourth message successfully received by the UE.

According to yet another embodiment, a method for operating a transmission-reception point (TRP) is provided. The method comprises the following steps: receiving a plurality of MSGs 1; performing a listen before talk (listen before talk, LBT) procedure in a plurality of directions based on the received plurality of MSGs 1, the LBT procedure indicating a first set of successful LBT directions; transmitting one or more MSG2 according to a first set of successful LBT directions; receiving one or more MSGs 3; determining whether one or more MSGs 3 map to the same UE; in response to determining that one or more MSGs 3 are not mapped to the same UE, performing an LBT procedure according to directions associated with the plurality of UEs, the LBT procedure indicating a second set of successful LBT directions; and transmitting one or more MSGs 4 to the plurality of UEs according to the second set of successful LBT directions.

Optionally, in any of the above aspects, the method for operating TRP further comprises: in response to determining that one or more MSGs 3 map to a single UE, merging identities of the one or more MSGs 3 to the single UE; performing an LBT procedure according to a direction associated with the single UE, the LBT procedure indicating a third set of successful LBT directions; transmitting MSG4 to the single UE according to the third group successful LBT direction; a hybrid automatic repeat request/acknowledgement (HARQ/ACK) is received, the HARQ/ACK including a mapping of successful MSG4.

According to yet another embodiment, a transmission-reception point (TRP) is provided. The TRP includes: a non-transitory memory including instructions; one or more processors in communication with the memory, the one or more processors executing instructions to: receiving a plurality of MSGs 1; performing a listen before talk (listen before talk, LBT) procedure in a plurality of directions based on the received plurality of MSGs 1, the LBT procedure indicating a first set of successful LBT directions; transmitting one or more MSG2 according to a first set of successful LBT directions; receiving one or more MSGs 3; determining whether one or more MSGs 3 map to the same UE; in response to determining that one or more MSGs 3 are not mapped to the same UE, performing an LBT procedure according to directions associated with the plurality of UEs, the LBT procedure indicating a second set of successful LBT directions; one or more MSGs 4 are sent to the plurality of UEs according to the second set of successful LBT directions.

Optionally, in any of the above aspects, the one or more processors further execute instructions to: in response to determining that one or more MSGs 3 map to a single UE, merging identities of the one or more MSGs 3 to the single UE; performing an LBT procedure according to a direction associated with the single UE, the LBT procedure indicating a third set of successful LBT directions; transmitting MSG4 to the single UE according to the third group successful LBT direction; a hybrid automatic repeat request/acknowledgement (HARQ/ACK) is received, the HARQ/ACK including a mapping of successful MSG 4.

Technical advantages are generally achieved by embodiments of the present disclosure, which describe protocols and methods for initial channel access in conjunction with directed LBT. These embodiments enable flexible initial channel access, robust initial access and lower initial delay based on spectral rules and traffic characteristics, and early refinement of beam selection for high frequency communications.

Drawings

For a more complete understanding of the present disclosure and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:

fig. 1 illustrates an exemplary wireless communication system in accordance with an exemplary embodiment described herein;

FIG. 2 illustrates an exemplary communication system that provides a mathematical representation of signals transmitted in the communication system;

FIGS. 3A and 3B illustrate block diagrams of embodiments of systems for analog beam steering and digital beam forming;

FIG. 4A shows a diagram of a wide beam pattern with a small number of antennas at low frequencies;

fig. 4B shows a diagram of a narrow beam pattern with a large number of antennas at high frequencies;

fig. 5 shows a diagram of a transition between UE operation modes;

FIG. 6 shows a diagram of system information provision;

fig. 7 shows a diagram of the main steps of a random access procedure;

fig. 8 shows a diagram of a master information block (master information block, MIB) synchronized with a UE;

fig. 9 illustrates a diagram of a method for a UE to use LBT/non-LBT configuration according to an example embodiment disclosed herein;

fig. 10 illustrates a diagram of a method for UE initial channel access by a directed LBT including a valid duration according to an example embodiment disclosed herein;

fig. 11 illustrates a diagram of a UE method for DBTW in accordance with an example embodiment disclosed herein;

FIG. 12 illustrates a diagram of an exemplary embodiment of a discovery burst disclosed herein;

fig. 13 shows a diagram in which PRACH preambles associated with SSBs are divided into subsets corresponding to SSBs and CSI-RSs in a DB;

Fig. 14 shows a diagram of a method for a UE when MSG1 is CSI-RS based, according to an example embodiment disclosed herein;

fig. 15 is a diagram illustrating a method for a UE to transmit MSG1 in multiple directions according to an example embodiment disclosed herein;

fig. 16 illustrates a diagram of an exemplary embodiment of a UE reply by acknowledging a single ACK message for multiple MSGs 4 as disclosed herein;

fig. 17 is a diagram illustrating a method by which a gNB merges multiple MSGs 1 transmitted from the same UE into a single identity according to an exemplary embodiment disclosed herein;

fig. 18 illustrates a diagram of a method for a UE to transmit multiple MSGs 1 in a single identity according to an example embodiment disclosed herein;

fig. 19 illustrates a diagram of an exemplary embodiment of multi-directional sensing and transmission for initial channel access as disclosed herein;

FIG. 20 illustrates a block diagram of an embodiment processing system; and

fig. 21 shows a block diagram of an embodiment transceiver.

Corresponding numerals and symbols in the various drawings generally refer to corresponding parts, unless otherwise indicated. The drawings are drawn to clearly illustrate the relevant aspects of the embodiments and are not necessarily drawn to scale.

Detailed Description

The structure and use of the disclosed embodiments are discussed in detail below. It should be appreciated, however, that the present disclosure provides many applicable concepts that can be embodied in a wide variety of specific contexts. The specific embodiments discussed are merely illustrative of specific constructions and uses of embodiments and do not limit the scope of the disclosure.

In one exemplary embodiment, the functions or algorithms described herein may be implemented in software. The software may be comprised of computer executable instructions stored on a computer readable medium or computer readable storage device (e.g., one or more non-transitory memories or other types of hardware-based local or networked storage devices). Further, such functions correspond to modules that may be software, hardware, firmware, or any combination thereof. Multiple functions may be performed in one or more modules as desired, and the described exemplary embodiments are merely examples. The software may be executed on a digital signal processor, ASIC, microprocessor, or other type of processor operating on a computer system (e.g., a personal computer, server, or other computer system) to thereby transform such a computer system into a specifically programmed machine.

Fig. 1 illustrates an exemplary wireless communication system 100. Communication system 100 includes an access node 110 having a coverage area 111. Access node 110 serves a plurality of User Equipments (UEs) including UE 120 and UE 122. The transmission from access node 110 to the UE is referred to as DL transmission and occurs on the downlink channel (shown as solid arrows in fig. 1), while the transmission from the UE to access node 110 is referred to as UL transmission and occurs on the uplink channel (shown as dashed lines in fig. 1). Services may be provided to a plurality of UEs by a service provider connected to access node 110 through a backhaul network 130 (e.g., the internet). The wireless communication system 100 may include a plurality of distributed access nodes 110.

In a typical communication system, there are several modes of operation. In the cellular mode of operation, communication with multiple UEs is through access node 110, while in the device-to-device mode of communication, such as in the proximity services (proximity service, proSe) mode of operation, direct communication between UEs is possible. An access node may also be commonly referred to as a NodeB, an evolved NodeB (eNB), a next generation NodeB (nb), a master eNB (MeNB), a secondary eNB (SeNB), a master nb (MgNB), a secondary nb (nb), a network controller, a control node, a base station, an access point, a transmission point (transmission point, TP), a cell, a carrier, a macrocell, a femtocell (femtocell), a picocell (pico cell), a relay, a customer premise equipment (customer premises equipment, CPE), and the like. The UE may also be commonly referred to as a mobile station, mobile device, terminal, user, subscriber, site, communication device, CPE, relay, integrated access and backhaul (Integrated Access and Backhaul, IAB) relay, etc. It is noted that when using relays (based on relays, pico cells, CPEs, etc.), especially when using multi-hop relays, the boundary between the controller and the node controlled by the controller may become ambiguous and a dual node (e.g. controller or node controlled by the controller) deployment, wherein the first node providing configuration or control information to the second node is considered to be the controller. Also, the concept of UL and DL transmission can be extended.

A cell may include one or more bandwidth parts (BWP) of UL or DL allocated for a UE. Each BWP may have its own BWP-specific parameter set and configuration. It should be noted that not all BWP need to be active simultaneously for the UE. One cell may correspond to one or more carriers. In general, one cell (e.g., primary cell (PCell) or secondary cell (SCell)) is a component carrier (e.g., primary component carrier (primary component carrier, PCC) or secondary CC (SCC)). For some cells, each cell may include multiple carriers in the UL, one carrier being referred to as an UL carrier with associated DL or a non-supplemental UL (non-SUL) carrier, the other carriers being referred to as Supplemental UL (SUL) carriers without associated DL. A cell or carrier may be configured with a slot or subframe format that includes DL and UL symbols and is considered to operate in a time division duplex (time divisionduplex, TDD) mode. Typically, for the unpaired spectrum, the cell or carrier is in TDD mode, while for the paired spectrum, the cell or carrier is in frequency division duplex (frequency division duplexed, FDD) mode. The access node may provide wireless access according to one or more wireless communication protocols, such as long term evolution (long term evolution, LTE), LTE-advanced (LTE-a), 5G LTE, 5G NR, high speed packet access (high speed packet access, HSPA), wi-Fi 802.11a/b/G/n/ac, and so on. For simplicity, only one access node and two UEs are shown, but it is understood that a communication system may employ multiple access nodes capable of communicating with multiple UEs.

Fig. 2 illustrates an exemplary communication system 200, the exemplary communication system 200 providing a mathematical representation of signals transmitted in the communication system. The communication system 200 includes an access node 205 in communication with a UE 210. As shown in fig. 2, the access node 205 uses a transmit filter v and the UE 210 uses a receive filter w. Both the access node 205 and the UE 210 use linear precoding or combining. Let H be N of a multiple-input multiple-output (MIMO) system _rx ×N _tx Matrix, i.e. with N _tx Multiple transmit antennas and N _rx And a plurality of receiving antennas. Dimension N _tx The transmit filter v of x Ns enables the transmitter to precode or beamform the transmit signal, where Ns is the number of layers, ports, streams, symbols, pilots, messages, data, or known sequences transmitted. The receive filter w of the multi-antenna system has a dimension N _rx X Ns, and represents a combining matrix, which is generally according to w ^H y is applied to the received signal y. The above description is for transmissions from the access node 205 to the UE 210, i.e. DL transmissions. The transmission can also take place in the opposite direction (UL transmission), for which the channel matrix becomes H in the case of TDD ^H (wherein H ^H Is a Hermitian matrix of the channel model H), w may be regarded as a transmit filter and v may be regarded as a receive filter. The w used for transmission and the w used for reception may be the same or different, as well as v.

The DL (or forward) channel 215 between the access node 205 and the UE 210 has a channel model or response H, while the UL (or backward, or reverse) channel 220 between the UE 210 and the access node 205 has a channelModel or response H ^H . (another convention is that the UL channel is denoted as H ^T Which is a transpose of the channel model H). Although fig. 2 depicts only one access node and one UE, communication system 200 is not limited to this case. Multiple UEs may be served by an access node on different time-frequency resources (e.g., in a frequency-division-time-division multiplexed (frequency division multiplexed-time division multiplexed, FDM-TDM) communication system, such as in a typical cellular system) or on the same time-frequency resources (e.g., in a multi-user MIMO (MU-MIMO) communication system, where multiple UEs are paired together and transmissions to each UE are precoded separately). Among paired UEs, there is intra-cell interference.

Moreover, multiple access nodes may also be present in the network, some of which may serve the UE 210 in a joint transmission manner (e.g., coherent joint transmission, incoherent joint transmission, coordinated multipoint transmission, etc.), a dynamic point-switch manner, etc. Some other access nodes may not serve the UE 210 and their transmissions to their own UE may cause inter-cell interference to the UE 210. The scenario of multiple access nodes and multiple UEs with access nodes serving as UEs and MU-MIMO is the scenario considered herein.

One way to increase network resources is to utilize more and more available spectrum resources that include not only licensed spectrum resources of the same type as the macro, but also licensed spectrum resources of a different type than the macro (e.g., the macro is an FDD cell, but a small cell may use both FDD and TDD carriers), as well as unlicensed spectrum resources and shared licensed spectrum; some of the spectral resources are located in a high frequency band, e.g., 6GHz to 60GHz. Unlicensed spectrum is generally available to any user, but subject to regulatory requirements. The shared licensed spectrum is also not operator specific. Traditionally, cellular networks do not use unlicensed spectrum, as it is often difficult to ensure quality of service (quality of service, qoS) requirements. Operation on unlicensed spectrum mainly includes wireless local area networks (wireless local area network, WLAN), such as Wi-Fi networks. Due to the fact that licensed spectrum is often scarce and expensive, the utilization of unlicensed spectrum by cellular operators may be considered. It should be noted that TDD is commonly used in both the high frequency band and the unlicensed/shared licensed band, and thus communication can be performed using channel reciprocity.

There is typically no pre-coordination between multiple nodes operating on the same frequency resource over unlicensed spectrum. Accordingly, a content-based protocol (CBP) may be used. CBP is defined as:

Cbp— "a protocol that allows multiple users to share the same spectrum by: defining events that must occur when two or more transmitters attempt to access the same channel at the same time, and establishing rules by which one transmitter provides reasonable opportunities for operation for the other transmitters. Such a protocol may consist of a procedure for initiating a new transmission, a procedure for determining the status of the channel (available or unavailable), and a procedure for managing retransmissions in case the channel is busy. "

Note that the status of busy channels may also be referred to as channel unavailable, channel not clear, channel occupied, etc., and the status of idle channels may also be referred to as channel available, channel clear, channel unoccupied, etc.

One of the most commonly used CBPs is the "listen before talk" (listen before talk, LBT) operation procedure in IEEE 802.11 or WiFi, which can be found in, for example, "wireless LAN medium access control (mediumaccess control, MAC) and physical layer (PHY) specifications", IEEE standard 802.11-2007 (IEEE standard 802.11-1999 revisions), the entire contents of which are hereby incorporated by reference. It is also known as carrier sense multiple access collision avoidance (carrier sense multiple access with collision avoidance, CSMA/CA) protocol. Carrier sensing is performed before any transmission attempt and only when the carrier is sensed to be idle, otherwise a random back-off time for the next sensing is applied. Listening is typically done through a CCA procedure to determine if the power in the channel is below a given threshold.

Fig. 3A and 3B are block diagrams of embodiments of systems 300 and 350 for analog beam steering plus digital beam forming. The system 300 in fig. 3A includes a baseband component 302 for digital processing, a plurality of RF chain components 304, a plurality of phase shifters 306, a plurality of combiners 308, and a plurality of antennas 310. The map may be used for transmission or reception. For simplicity we describe a graph assuming this is for transmission; the reception can be understood similarly. Each RF chain 304 receives a weighting factor (or weight, p1, … …, pm, as shown) from the baseband component 302. The set of weighting factors forms a digital precoding vector, a precoding matrix, a beamforming vector or a beamforming matrix for the transmission. For example, the precoding vector may be [ p1, …, pm ]. When transmitting a plurality of layers/streams, the baseband unit may generate a weighting factor using a precoding matrix, each column (or row) of the matrix being applied to the transmitted layers/streams. Each RF chain 304 is coupled to a plurality of phase shifters 306. In theory, the phase shifter may apply any phase shift value, but in practice only a few possible phase shift values, e.g. 16 or 32 values, are typically applied. Each RF chain 304 generates a narrow beam 312 oriented in a direction determined by the settings on the phase shifter 306 and combiner 308. If the phase shifter can apply any phase shift value, the beam can be directed in any direction, but if only a few phase shift values can be used, the beam can be one of a few possibilities (e.g. in the figure, a solid narrow beam is selected by setting a specific phase shift value in the RF chain, and this beam is among all possible narrow beams shown as solid and dashed beams corresponding to all possible phase shift values). Each RF chain selects one such narrow beam and all such narrow beams selected by all RF chains will be further superimposed. The manner in which the superposition is accomplished is based on a digital weighting factor. This factor may either strengthen or weaken the beam from the RF chain, and thus different sets of factors may produce different stacks in the spatial domain; in the figure, a particular beam 314 is shown. In other words, by selecting different digital weighting factors, different beams 314 may be generated. Digital operation may be generally referred to as (digital) beamforming or precoding, and analog operation as (analog) beam steering or phase shifting, but sometimes without explicit distinction.

The system 350 in fig. 3B is similar to the system 300 in fig. 3A, except that the corresponding combiners 308 in each RF chain 302 are connected to each other.

To meet regulatory requirements for operation in unlicensed spectrum and to coexist with other radio access technologies (radio access technology, RATs), such as Wi-Fi, transmissions on unlicensed spectrum cannot be continuous or persistent in time. Rather, on/off or opportunistic transmission and measurement as needed may be employed.

Furthermore, for operation in the high frequency range, in particular in the 28GHz to 60GHz frequency range, they generally belong to the millimeter wave (mmWave) range, which has propagation characteristics that are distinct from microwaves (generally lower than 6 GHz). For example, millimeter waves have a higher path loss over distance than microwaves. Thus, the high-band is more suitable for small cell operation than for macro cell operation, and typically relies on beamforming using a large number of antennas (e.g., >16, sometimes even possibly hundreds) for efficient transmission. Note that at high frequencies, the wavelength, antenna size, and antenna spacing may be smaller than at low frequencies, so it is feasible to equip the node with a large number of antennas. Thus, the beam formed by a large number of antennas may be very narrow, e.g. a beam width of 10 degrees or even less. In sharp contrast, in conventional wireless communications, the beam width is typically much wider, such as tens of degrees. Referring to fig. 4A, a wider beam pattern 402 with a small number of antennas at low frequencies is shown, and referring to fig. 4B, a narrow beam pattern 404 with a large number of antennas at high frequencies is shown. In general, narrow beams are considered to be a major new feature of millimeter waves. As a general rule of thumb, the beamforming gain of massive MIMO can be roughly estimated as n×k, where N is the number of transmit antennas and K is the number of receive antennas. This is because the 2-norm of the channel matrix H scales approximately by (nxk) 1/2, so if the precoding vector of the transmitting node is p and the combining vector of the receiving node is w, the composite channel is w' Hp, and by properly selecting w and p, the energy gain of the composite channel can reach nxk, much higher than with fewer antennas.

At high frequency bands, e.g. 60GHz, directional communication is preferred in order to mitigate the effects of high path loss. Thus, when using directional communication, specific problems need to be considered, which are exacerbated in unlicensed high frequencies. When the LBT operation is performed using a narrow (high gain) antenna, the operation is referred to as directional LBT.

Directional antennas are used due to the high attenuation of the millimeter wave band. The present disclosure defines an initial access procedure for directional beam sensing and communication that allows a UE to perform initial channel access to communicate in unlicensed frequency bands in multiple spatial directions required for reasons such as robustness, spatial diversity, multi-TRP and multi-link connections, use of directional sensing and directional communication.

The proposed solution expands the existing random access channel access of NR to be compatible with the channel access of unlicensed millimeter wave band.

There are some geographical areas (e.g., the united states) where LBT procedures are not mandatory for channel access. Therefore, for the case where the traffic is low or communication devices using the channel are few, the LBT procedure may not be necessary. The LBT procedure is enabled only when the channel is heavily used or experiences a large number of collisions. Such decisions, which may be left to be implemented at the base station, have to be communicated to the user equipment. Thus, the wireless network should be able to dynamically enable or disable the LBT procedure and inform UEs within its coverage area.

The UE may be in any of three states. When the RRC connection is established, the UE is in an rrc_connected ("CONNECTED") state or an rrc_inactive ("INACTIVE") state. If this is not the case, i.e. no RRC connection is established, the UE is in rrc_idle ("IDLE") state. In the rrc_idle state, the UE performs neighbor cell measurement, cell selection (reselection), acquires system information (system information, SI) and may send an SI request (if configured). The transition between UE operation modes is shown in fig. 5.

Initial channel access is defined as the set of procedures performed by the UE for cell search and cell selection. For the cell selection procedure, the UE only needs to search for the strongest cell on each frequency, except for the operation of access with shared spectrum channels, where the UE can search for the next strongest cell. Once a suitable cell is found, the cell should be selected.

Cell search is a process in which a UE acquires time and frequency synchronization with a cell and detects a physical layer cell ID of the cell.

The UE assumes that the reception opportunities of the physical broadcast channel (physical broadcast channel, PBCH), PSS, and SSS are in consecutive symbols and forms an SS/PBCH block. One or more SS/PBCH blocks constitute a SS/PBCH set. The SS/PBCH set is limited to a 5ms window, which is repeated periodically. For initial cell selection, the User Equipment (UE) assumes a default SS/PBCH set period of 20ms. Synchronization during initial access is a two-step identification procedure (via PSS and SSS) to provide both timing (symbol and slot only) and frequency synchronization. Decoding the master information block (master information block, MIB) after demodulating the PBCH provides a system frame number and enables reception of a control/data channel (PDCCH/PDSCH). During initial access where the UE performs random access (through PRACH), SIB1 (transmitted through PDCCH/PDSCH) may need to be detected.

For operation of shared spectrum channel access, the UE assumes that the transmission of the SS/PBCH block in the field (5 ms) is within a discovery burst transmission window starting from the first symbol of the first slot in the field.

The UE assumes that one or more SS/PBCH blocks indicated by ssb-positioninburst may be transmitted within the discovery burst transmission window and have candidate SS/PBCH block indices corresponding to the SS/PBCH block indices provided by ssb-positioninburst. The value of RSRP-ThresholdSSB indicates the RSRP threshold for selecting SSB for the 4-step RA type (type 1). Similarly, for a 2-step RA, the field msgA-RSRP-ThresholdSSB provides an RSRP threshold for selecting SSB for the 2-step RA type (type 2). The main steps of system information provision and random access are shown in fig. 6 and 7.

After the UE selects SSB (SS/PBCH block), the UE transmits RACH preamble on PRACH occasion. There are RACH preamble formats (A1-A3, B1-B4, C0, C1) defined for NR. The duration of the RACH preamble varies between 2 and 12 symbols within the same time slot, i.e. PRACH time slot. The preamble transmission may occur in a subset of configurable time slots (PRACH slots) that repeat each PRACH configuration period. The PRACH configuration period may be configured between a range of 10ms and 160 ms. Within a PRACH slot, multiple PRACH occasions may exist consecutively in time and frequency.

Channel access to shared spectrum (unlicensed spectrum) below 6GHz relies on Discovery Burst (DB) methods. DB refers to DL transmission bursts comprising a set of signals and/or channels confined within a window and associated with a duty cycle.

The gNB initiated transmission includes at least an SS/PBCH block consisting of a primary synchronization signal (primary synchronization signal, PSS), a secondary synchronization signal (secondary synchronizationsignal, SSS), a physical broadcast channel (physical broadcast channel, PBCH) with associated demodulation reference signals (demodulation reference signal, DM-RS), and may also include a control resource set (CORESET) for PDCCH scheduling of PDSCH with SIB1 and PDSCH carrying SIB1 and/or non-zero power CSI reference signals (CSI reference signal, CSI-RS).

The discovery burst transmission window (discovery burst transmission window, DBWT) represents a time window for retransmitting discovery bursts.

In licensed spectrum, the transmission of SS/PBCH blocks is well defined in terms of timing. In unlicensed spectrum, the LBT procedure prior to SS/PBCH transmission cannot guarantee success, so the gnbs can skip their transmission until the channel becomes available.

The type of LBT is also different according to DB duration. For longer DBs, i.e. in case of a transmission initiated by the gNB with only discovery bursts or with discovery bursts multiplexed with non-unicast information, a full LBT (type 1DL LBT) is required, where the transmission duration is more than 1ms or the transmission results in a discovery burst duty cycle exceeding 1/20.

When the transmission initiated by the gNB has only discovery bursts or has discovery bursts multiplexed with non-unicast information, a short deterministic short LBT (type 2 DL) is necessary, where the transmission duration is at most 1ms and the discovery burst duty cycle is at most 1/20.

In unlicensed bands (below 6 GHz), DBTW is always present. Without enabling/disabling operations, NR-U always performs in the same manner with respect to DBTW. More specifically, the UE behavior of NR-U during DBTW in the unlicensed band of <6GHz is specified in TS 38.213 as follows:

"for shared spectrum channel access operation, the UE assumes that the transmission of the SS/PBCH block in the field (5 ms) is within a discovery burst transmission window starting from the first symbol of the first slot in the field. The UE assumes that one or more SS/PBCH blocks indicated by ssb-locationinburst may be transmitted within the discovery burst transmission window and have candidate SS/PBCH block indices corresponding to the SS/PBCH block indices provided by ssb-locationinburst. ssb-locationinburst is a bitmap (up to 64 bits) for indicating the SS/PBCH actual transmission. For operation of shared spectrum channel access, the UE assumes that SS/PBCH blocks in the serving cell that are within or across the same discovery burst transmission window are quasi co-located with respect to the average gain, quasi co-located 'typeA' and 'typeD' attributes, when applicable. "

In the unlicensed band of <6GHz, the gNB may transmit in fewer SS/PBCH transmission opportunities due to LBT failure. In the licensed band, the gNB transmits in each SS/PBCH transmission opportunity. Furthermore, in the licensed band, the number of transmission opportunities for the SS/PBCH block is smaller than the number of transmission opportunities for the SS/PBCH in the unlicensed spectrum for the same duration of the 5ms DBTW.

In the current implementation, the random access procedure may be affected by LBT failure of each step. A robust initial channel access method is necessary which allows for continuity despite the fact that some spatial directions are affected by interference.

Existing processes rely on the selection of a single SSB direction. However, when the UE transmits MSG1 (PRACH), when using directional LBT, the direction may be found busy despite the fact that other available directions meeting the SSB RSRP threshold may be available and used.

In the millimeter wave unlicensed band, when a random access preamble (MSG 1) is transmitted in a single PRACH opportunity (PRACH opportunity, PO), there is an increased risk that this preamble cannot be received at the gNB due to the additional path loss and interference of other users sharing the same band. The additional path loss is caused by higher frequencies and possible misalignment between the transmit and receive beams, repeating MSG1 in multiple UL directions will increase the chance that the gNB will receive MSG1 correctly.

When the gNB reverts to MSG2, the LBT is likely to fail if a single spatial filter (direction) is used to orient the LBT. Using multiple directional LBTs and multiple directions, MSG2 transmission provides additional robustness. Similarly, for MSG3 and MSG4.

For directional LBT signaling for initial access, the gNB should be able to inform the UE of the mandatory use of LBT and the type of LBT before or during the initial channel access step when the UE is in rrc_idle state and later when the UE is in rrc_connected or rrc_inactive state. In this disclosure, we have solved a number of problems associated with initial channel access in the millimeter wave unlicensed band.

In one embodiment, the LBT procedure of the first step of the random access (MSG 1) transmission is applied as a default procedure. For example, the UE may perform a short deterministic LBT, or a full LBT, prior to MSG1 transmission. The LBT procedure should cover the direction of MSG1 transmission.

In different embodiments, the default channel access of the UE for MSG1 (RACH preamble) transmission is regarded as short control signaling, so the UE does not perform LBT before MSG1 transmission. To meet the short control signaling, the duty cycle of the transmission should be less than or equal to 10%. Thus, the total transmission duration for this operation should not be longer than 10ms during a 100ms time interval. This can be easily satisfied even with multiple repetitions, considering that the duration of MSG1 and MSG3 are each less than one slot (one slot duration at 120kHz SCS is 125 us).

In a preferred embodiment, when the LBT procedure or short control signaling is not the default mode of UE operation of MSG1, the gNB should be able to inform the UE that LBT is enabled or disabled prior to MSG1 transmission.

In one embodiment, this may be done in a master information block (master information block, MIB) that may signal LBT enabled through a single bit field, as shown in fig. 8. For example, if there is a single subcarrier spacing (subcarrier spacing, SCS) common (e.g., 120 kHz), the sub-subcarrier spacing command bits in the MIB may be (re) used to signal whether LBT is enabled, as shown below.

The subclrierspacengcommon value of scs15 or 60 signals that LBT is mandatory (enabled), scs30 or 120 indicates that LBT is not required (not enabled).

When LBT is enabled, range enablement may be decided a priori. For example, in one embodiment, the range of LBT enablement is used only for transmitting MSG1, and the gNB may enable the LBT procedure in its MSG2 (RAR) response. In a different embodiment, the MIB may signal that LBT is enabled for all operations related to initial channel access, but in another embodiment, the MIB may signal that LBT is enabled indefinitely until the UE receives an LBT disable signal.

In a preferred embodiment, LBT (enabled/disabled) or equivalently non-LBT (enabled/disabled) may be signaled in system information such as SIB 1. For example, a new field may be added in cellaccessrelateinfo to signal whether LBT is enabled, and the type of LBT required for MSG1 and MSG3, as follows.

In the proposed embodiment, the value of lbt_enabled signals whether LBT is required after initial access, while msg1_lbt and msg3_lbt specify the type of LBT for MSG1 and MSG3, respectively.

Similar fields in SIB1 are used for two-step random access MSGA. Note that the LBT procedure required for the 4-step RACH and the 2-step RACH may be different.

After the UE decodes SS/PBCH and PDCCH (in CORESET # 0), the corresponding SIB1 in PDSCH contains a field that signals the use of LBT (LBT enabled) or NoLBT (LBT disabled), in which case SIB1 provides additional information about the LBT procedure type of initial access. For example, the gNB may inform/request (via SIB 1) the UE to perform a one-time (shortLBT) LBT procedure before MSG1 and MSG3 in random access. In another embodiment, the gNB may signal to the UE that MSG1 may be sent as short control signaling without using any LBT procedure (NoLBT), and that MSG3 may be sent after a short (shortLBT) LBT or MSG3 with a complete LBT. Or any other combination thereof.

In different embodiments, the gNB may provide LBT configuration for MSG3 in SIB1, but this may be replaced by an LBT procedure from MSG3 provided in MSG2 of the gNB.

For MSG2:

the UE listens for a RA-RNTI scrambled PDCCH (DCI 1_0) transmission from the gNB within a period RAR-Window configured by a RAR-Window Length IE in the SIB message

UE searches PDCCH DCI in the type 1PDCCH public search space

Once the UE can successfully decode the PDCCH, it obtains RB resource information to receive a downlink transport block transmitted through the PDSCH.

The UE attempts to decode the PDSCH carrying Mgs2 random access response (random access response, RAR) data and checks if the RAPID in the RAR matches the RAPID allocated to it.

PDCCH and PDSCH transmissions should be carried in the same subcarrier spacing (subcarrier spacing, SCS) and cyclic prefix indicated in SIB 1.

In one embodiment, information of the LBT type of MSG3 may be included in the PDCCH, e.g., in this particular example only, a new data indicator bit may signal that MSG2 may be transmitted without LBT or with short LBT.

The PDCCH scrambled with the RA-RNTI schedules resources for the PDSCH (Msg 2). The UE parses the received PDSCH to find a specific MAC CE. The MAC CE contains an upstream grant to MSG 3.

In different embodiments, the LBT type of MSG3 is provided in a MAC CE included in the PDSCH (MSG 2), e.g., a field of the CSI request may be used to signal the NoLBT/shortLBT.

The LBT type (NoLBT, shortLBT, fullLBT) to be used by the UE after initial channel access may be conveyed by the gNB in SIB1 or MSG4 (MAC CE).

After the UE enters a CONNECTED state (rrc_connected), after initial access, LBT configuration may be provided by the gNB in various ways, such as RRC configuration, dynamic configuration of DCI via each UL schedule, or grant UL via configuration for semi-persistent scheduling or periodic scheduling.

Fig. 9 shows a diagram of an embodiment method 900 for UE operation when LBT or NoLBT configuration is provided for initial access.

In one embodiment, at step 905, MSG2 may indicate to the UE a change in LBT configuration (e.g., enable or disable LBT) relative to the LBT configuration indicated in MIB or SIB 1. The UE will apply the last received configuration to MSG3 or for further transmission until LBT configuration changes.

In another embodiment, MIB information provided in SS/PBCH broadcast may differ between SS/PBCH transmissions in a field and thus may not be the same for each directional transmission of SS/PBCH from the gNB. In this case, when the UE transmits MSG1 in the SS/PBCH reception direction, the UE should use LBT procedure configuration information received in the MIB from the SS/PBCH of the direction for its directional MSG1 transmission in step 907. That is, MSG1 and MSG3 transmitted in different directions may use different LBT procedure types based on MIB/SIB and MSG2 information on LBT.

However, in a different embodiment shown in method 1000 of fig. 10, the gNB may provide the effective duration of LBT enablement that the UE needs to use. For example, MSG2 may provide the UE with durations associated with different LBT procedure types. For example, for N1 slots starting from the first slot after the UE receives MSG1, the UE needs to perform LBT procedure type 1, and for the next N2 slots, the UE needs to perform LBT procedure type 2. After the N1+ N2 duration times out, the UE should fall back to the default type of LBT (e.g., full LBT). For example, such a solution would allow the UE to transmit free of LBT as short control signaling for a limited duration. We note that this signaling in MSG2 can be done in various ways when PDCCH schedules PDSCH (MSg 2) or when MAC CE is added in MSG 2.

An example of such signaling may be, for example, that the gNB (via MIB) allows MSG1 to send via short control signaling procedures without using LBT, in MSG2, some time constraints are provided when the UE is allowed to use short control signaling for MSG 3. If the timer expires due to, for example, the UE failing to complete the LBT procedure, the UE may need to send its MSG3 and further transmissions using some form of LBT.

All transmissions in the initial channel access may be considered part of the rrc_inactive state. In another embodiment, the LBT/NoLBT policy, including details of the initial channel access type, e.g., for LBT, may be provided to the UE in rrc_inactive mode over a paging channel (PCCH/PCH).

In the 3gpp RAN1 working group, which extends NR in the 52.6GHz spectrum band to 71GHz, the decision should take into account the discovery burst transmission window (discovery burst transmission window, DBTW), but this is not a mandatory requirement. In particular, for geographic areas where regulatory authorities do not mandate LBT (e.g., the united states), DBW should be enabled or disabled based on traffic density. For example, in a us deployment, LBT can only be enabled under conditions of higher traffic. In these cases, the DBW may also be enabled or disabled depending on the traffic conditions. It is clear that when LBT is not mandatory, there is less traffic (interference) from outside the network and network behavior in unlicensed spectrum may be closer to licensed spectrum behavior. Thus, the network should be able to enable or disable DBW and inform the UE of this.

The present disclosure provides means for enabling and disabling DBTWs and ways for UEs to take action based on this information.

In one embodiment, DBTW is enabled by default when channel access requires LBT. In this case, the UE will interpret the received SS/PBCH accordingly, including for example QCL type D between different SS/PBCH transmissions with the same SSB index.

In various embodiments, DBWT enablement may be advertised in a paging channel or MIB, for example, using one of the MIB reserved bits. Additional information about the DBTW duration and period may also be provided if the DBTW presence is provided by SIB1 (or other system information block) or through RRC. For example, SIB1 may contain the field DBTW-Duration ENUMERATED {0ms,1ms,2ms,2.5ms,5ms }, where 0ms represents disabling DBTW. Similarly, a period may be provided by DBTW_ Period ENUMERATED {1ms,2ms,4ms,5ms,10ms,20ms }, where the period requires a duration greater than or equal to DBTW, as shown below.

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In different embodiments, the DBTW structure may also be provided by SIB 1. For example, the DBWT may contain a CSI-RS signal and SS-PBCH, PDCCH, PDSCH.

In this case, the structure may be signaled as follows.

DBTW-Structure SEQUENCE(SIZE(1...maxDBTW)OF DBTW-Components)

DBTW-Components CHOICE{SS-PBCH,CORESET#0,PDCCH,PDSCH,CSI-RS}

When CSI-RS is present in the DBTW, the UE may report the best CSI-RS or CSI-RS measurements (RSRP), for example, in MSG 3. The SSB index and its strength measurement may also be reported in MSG 3.

Reporting may or may not be enabled in SIB1 information for DBTW. For example, the number of the cells to be processed,

DBTW-Reporting ENUMERATED{None,SSB 1,SSB 2,…,CSI-RS1,CSI-RS2,…,CSI-RS N},

wherein the system information specifies the number of SSBs and/or CSI-RSs to be reported. In different embodiments, the SIBs only provide thresholds for CSI-RS and SSB to be reported, respectively. Only those SSBs and CSI-RSs above their respective thresholds are reported. They may be different. In this case, the UE will report indexes of CSI-RS and SS-PBCH blocks satisfying the threshold condition, respectively. These reports may be included in MSG3 of the RACH procedure. Fig. 11 illustrates an exemplary embodiment of a DBTW in a method 1100.

A new method for random access when using directional sensing and directional transmission and LBT enabled is presented below. Several embodiments are presented.

In one embodiment, LBT is required and discovery burst transmission windows (discovery burst transmission window, DBWT) are enabled. The gNB may continue with the directional (e.g., one-time) LBT before sending the Discovery Burst (DB). In this case, the gNB may transmit the SS/PBCH only in those directions in which the channel is found to be idle, similar to those in NR-U. These LBT directions are protected by SSB, CORESET #0, SIB1, CSI-RS and RACH transmissions. Each DB is expected to contain PDCCH and PDSCH carrying SIB1 system information in addition to SS/PBCH blocks, all of which are transmitted in the same direction (QCL-type D).

During system information acquisition (for initial access), the UE acquires information required for configuration of PRACH parameters (PRACH preamble format, time resources, frequency resources) and parameters (index of logical root sequence table, cyclic shift, set type) for MSG1 generation.

In a preferred embodiment, a solution for signaling and using CSI-RS in an initial access is disclosed, wherein in addition to system information (SIB 1), the gNB may provide information of DB structure, e.g. presence of CSI-RS, and also instruct the UE to report, e.g. the best reference signal for multiple SS/PBCH and/or CSI-RS measurements in MSG 3.

When included in DBTW, the CSI-RS signal will be quasi co-located with respect to doppler shift, doppler spread, average delay, delay spread, and spatial Rx parameters (if applicable) with corresponding SSBs, where the best reference signal may be defined as a signal with an intensity above a threshold. We note that SSB is chosen similarly to what is specified in certain criteria (above a certain threshold). In this disclosure, we extend the concept and provide additional thresholds for CSI-RS signal selection. The thresholds provided in SIB1 may be different for SS/PBCH blocks and CSI-RS signals.

In one embodiment, SIB1 or PDSCH MSG2 may carry information required by the UE to receive CSI-RS associated with SSB, such as scramblingID or sequenceGenerationConfig, firstOFDMSymbolInTimeDomain and frequencydomaimallocation, which may be a number of limited entries in a configuration table dedicated to RACH.

In a preferred embodiment, the scrambling id or sequenceGenerationConfig, firstOFDMSymbolInTimeDomain and frequencydomainalllocation for CSI-RS configuration are provided by SSB indexes by default. For a single SSB index, multiple CSI-RSs may be associated, where the number of CSI-RSs may be specific to the discovery burst. The MSG2 PDCCH may trigger CSI-RS reporting.

In another embodiment, SIB1 information may inform the UE that different CSI-RSs in the DBWT map to different random preambles, so the UE may use CSI-RS associated preambles for MSG1 instead of SS/PBCH associated PRACH preambles. In this case, the triggering of the CSI-RS measurement is provided by the SSB itself. We note that since CSI-RS and SSB are quasi co-sited, CSI-RS measurements do not require additional beam switches. For example, CSR-RS1 may be mapped to a first half of a random preamble and CSI-RS2 may be mapped to a second half of the CSI-RS preamble, as shown in FIG. 12.

This mapping may be used for beam refinement during the initial channel access phase. As shown in fig. 13, one example of PRACH preamble associated with CSI-RS may be that a set of all preambles (up to 64) associated with SSBs may be divided into subsets corresponding to SSBs and CSI-RS in DB. The UE transmits the PRACH preamble using the same spatial filter used to receive the CSI-RS, using the PRACH preamble associated with the CSI-RS. Thus, the UE will inform the gNB of the preferred SSB beam and the preferred CSI-RS beam, which may be a refinement of the SSB beam.

In one embodiment, the PDCCH and PDSCH providing the system information SIB1 may carry information about the COT and LBT types of the UE. For example, the gNB may signal an ongoing COT, its resources, and the remaining duration until the COT times out. Since SS/PBCH, CORESET #0, PDCCH, PDSCH belong to the same DB and they are QCL-D type (transmitted in the same direction), the associated COT may also be directional COT. This means that the responding device, e.g. UE, performing the initial access needs to adhere to the COT configuration indicated in the directed SIB1, e.g. the resources of the COT, the type, direction and duration of the LBT including the energy detection threshold.

The UE performs an initial channel access scan in a plurality of spatial directions and decodes SS/PBCH received in the discovery burst. The UE collects/measures a plurality of discovery bursts (each discovery burst including SS/PBCH) and reserves N plurality of spatial directions associated with the best SS/PBCH for the next step of random access. For example, those directions of SS/PBCH transmissions that have RSRP or RSSI above a threshold, where the threshold is predefined or provided by the gNB SIB1 information. Based on the received system information, the UE may also measure CSI-RS associated with each SS/PBCH. In one embodiment, the gNB may indicate to the UE in SIB1 that the spatial filter (direction) of the UE for transmitting the RACH preamble (MSG 1) is based on (TCI state) SS/PBCH block QCL-D or CSI-RS transmitted during DB or a combination thereof.

In another embodiment shown in method 1400 of fig. 14, when the system information provides an indication of the presence of CSI-RS in the DB, it may also provide a way to generate RACH preambles for UE MSG 1. For example, the maximum number of preambles associated with an SS/PBCH block (64 in the current NR specification) may be divided into multiple sets, each set corresponding to a CSI-RS, so when a UE generates a RACH preamble (MSG 1), the RACH preamble may indicate the strongest CSI-RS associated with the SS/PBCH. Although the number of preambles of the CSI-RS direction is less than 64, the CSI-RS itself may be transmitted with a narrower beam than the SS/PBCH block, so the probability of possible collision between UEs transmitting the same preamble remains low.

When LBT is enabled (mandatory), the UE performs directed LBT in a direction associated with a RACH Opportunity (RO) provided in the received system information. LBT may each be used for a single direction or for several directions simultaneously.

In a preferred embodiment, the directional LBT may be of different types (as duration/backoff window and energy detection threshold) based on the system information (MIB, SIB 1) received from this direction. No specific LBT type for a specific SSB/CSI-RS is provided in the NR.

In order to transmit a RACH preamble in a RACH Opportunity (RO), the UE may need to perform an LBT procedure, as shown in method 1500 of fig. 15. The method preferably uses directional LBT, wherein the direction used is the direction associated with the corresponding SSB (or CSI-RS). If the UE tries to transmit multiple MSG1 (RACH preamble) in different directions, it may happen that only some of the directions pass the LBT procedure (channel idle). The UE transmits a preamble to the RACH only when the directed LBT finds an idle channel.

In this embodiment, after the UE repeats LBT and RACH preamble transmission operations up to N times, where N may be provided in a system information block by the gNB, for example. Note that the current NR specifications and designs do not prohibit the NR from transmitting multiple RACH preambles (MSG 1) in different directions.

MSG1 transmission is considered successful after successful receipt of a random access response containing a random access PREAMBLE identifier matching the transmitted preamble_index before the ra-response window timeout.

In the present disclosure, the RAR timer associated with ra-ResponseWindow starts with the last MSG1 transmission of a sequence of multiple MSGs 1 sent in multiple directions.

The timer indicates a maximum waiting time until a random access response (random access response, RAR) from the gNB. If the UE does not receive any RAR (MSG 2) from the gNB, after the timer expires, the UE may retransmit MSG1 or begin monitoring DB for other PRACH opportunities.

Based on the current NR design, when the gNB receives one or more RACH preambles (MSG 1), it has not yet knowledge of the sender identity. Thus, the gNB continues LBT in those directions that received each MSG1, and if any of these directions are found to be idle before the RAR timer times out, then the gNB responds with PDCCH scrambled with RA-RNTI and corresponding PDSCH, where the gNB schedules UL grants in the transmit direction for UE MSG 3.

The MSG2 (PDSCH) in the present technology (3 GPP NR) from the gNB contains information about: timing advance, resource allocation for MSG3, MCS for MSG3, TPC commands and CSI requests for MSG3 (unused), and temporary C-RNTI, backoff indicator (backoff indicator, BI) or random access preamble ID (random access preamble ID, RAPID) identifying random access preamble (MSG 1).

In one embodiment, in the present disclosure, the MSG2 (PDSCH) contains a resource reference for CSI-RS for additional channel measurements (e.g., beam refinement). If requested, the CSI-RS and/or SS/BCH block measurements may be reported in an MSG3 response from the UE.

In one embodiment, the MSG2 (PDSCH) may indicate the maximum number of reports and conditions for reporting, e.g., based on the received signal strength added to the CSI request indication.

In different embodiments, there are different TPC fields for SSB and for CSI-RS, so that if UE uses TCI state based on SS/PBCH block measurements for MSG3, UE should use TPC commands for MSG3 PUSCH indicated in MSG 2. If UE MSG3 is transmitting in the direction of the received CSI-RS, then the corresponding TPC will be selected, which may be different from the SS/PBCH based TPC for MSG 3.

When a DCI format is detected in response to a PUSCH transmission scheduled by a RAR UL grant or a corresponding PUSCH retransmission scheduled by DCI format 0_0 (where the CRC is scrambled by a TC-RNTI provided in a corresponding RAR message), the UE may assume that the PDCCH carrying the DCI format has the same DM-RS antenna port quasi co-location attribute as the UE uses for the SS/PBCH block associated with the PRACH, regardless of whether a TCI state for CORESET is provided for the UE, where the UE receives the PDCCH with the DCI format.

After the UE collects multiple MSG2 responses from the gNB, the UE must inform the gNB of its unique identity to the previously successfully sent MSG1 message.

In one embodiment, in MSG3, the UE uses a single one of the C-RNTIs provided by the gNB in the MSG2 response (e.g., the first C-RNTI received) to identify the UE itself. In MSG3, the UE provides a mapping or list or index in the table indicating the instance when the UE sends all received C-RNTI values in MSG1 or all MSG 2.

In various embodiments, the UE responds to the received MSG2 with MSG3, wherein MSG3 contains two C-RNTI values. One C-RNTI value is the C-RNTI value allocated by the gNB in the corresponding MSG2, while the other C-RNTI is the same for all MSGs 3 and may be the first received C-RNTI.

For example:

MSG3-1	C-RNTI 1	C-RNT 1
			MSG3-2	C-RNTI 2	C-RNT 1
MSG3-3	C-RNTI 3	C-RNT 1

in this way, the gNB can associate multiple received MSGs 1 to a single UE identity.

After the gNB receives one or more MSGs 3 from the UE, the gNB performs LBT operation if necessary and transmits MSG4 with contention resolution identity through PDSCH. In this message, the gNB maps all received MSGs 1 to a single UE identity based on the UE identity received in MSG 3.

In response to PDSCH reception with UE contention resolution and identity resolution (MSG 4), the UE transmits HARQ-ACK information in the PUCCH, wherein the UE acknowledges the unique identity.

In one embodiment, the gNB schedules multiple MSG4 transmissions to multiple directions, which correspond to a subset of MSG1 or MSG3 reception directions.

If the gNB transmits the same MSG4 in multiple directions after multiple directional successful LBTs, the gNB communicates the number of MSGs 4 transmitted in each direction, i.e., the number of expected ACKs from the UE.

In a preferred embodiment, we introduce the concept of multi-directional HARQ for directional LBT. When the UE (or gNB) receives multiple messages (from one or more direction-space receive filters), they may correspond to the same multi-directional HARQ process.

The multi-directional HARQ process is characterized by multiple directions, where the UE may use directional LBT before sending an ACK/NACK.

In other words, UL resource allocation of PUSCH/PUCCH corresponds to multiple directions that the gNB is able to monitor simultaneously (e.g., using multiple panels).

The UE attempts to direct the LBT towards the provided direction and sends an ACK/NACK for all received messages corresponding to the same multi-directional HARQ in the first direction through the LBT condition.

When the UE receives multiple MSGs 4 with contention and identity resolution, the UE acknowledges with an ACK message. The UE may need to perform LBT before sending the ACK. If one of the directional LBTs fails, the UE may attempt the other direction corresponding to the direction indicated by MSG4. The UE may acknowledge all received MSGs 4 in the first successful LBT direction.

In a preferred embodiment, the UE replies with a single ACK message acknowledging multiple MSGs 4 (e.g., bits dedicated to each MSG 4), as shown in fig. 16.

Fig. 17 shows a diagram of a method 1700 for an exemplary embodiment of combining multiple MSGs 1 transmitted from the same UE in a single identity. As shown in step 1701, the gNB receives a plurality of MSGs 1, and in step 1702, LBT is performed for the received MSG1 direction. The gNB transmits MSG2 in those directions in which the LBT was successful. In step 1704, the gNB receives one or more MSGs 3 and in step 1705, checks whether multiple MSGs 3 are mapped to the same UE.

In one embodiment, if multiple MSGs 3 are not mapped to the same UE, the gNB performs LBT for directions associated with multiple UEs and sends MSG4 to multiple UEs in a successful LBT direction.

In another embodiment, if multiple MSGs 3 map to the same UE, the gNB merges the identities into a single UE, performs LBT for the direction associated with that UE, and sends MSG4 to the single UE in the successful LBT direction, as shown in steps 1708-1710. The gNB then receives the HARQ/ACK with the mapping of successful MSG4, as shown in step 1711.

Fig. 18 shows a flow chart of an exemplary embodiment of multiple MSGs 1 transmitted in a single identity from the same UE. If multi-directional initial access is enabled, the UE identifies multiple SS/PBCH and CSI/RS directions, as shown in step 1801. In step 1802, the UE then performs LBT in multiple directions, and in step 1803, the UE transmits MSG1 (each preamble corresponding to SSB or CSIRS) in multiple directions. The UE then receives a plurality of MSGs 2 corresponding to its MSG1 transmissions, as shown in step 1804. The UE performs a directed LBT in which the UE transmits one or more MSGs 3 in the direction of a successful LBT, where itself is identified as the only sender of the multiple MSGs 1, as shown in steps 1805 and 1806. The UE then receives one or more MSGs 4, and the UE sends HARQ/ACKs with the mapping of successful MSGs 4 to the gNB, as shown in steps 1807 and 1808.

Fig. 19 illustrates an exemplary embodiment of multi-directional sensing and transmission for initial channel access. The gNB or M-TRP transmits a plurality of directed SSB burst messages. The UE determines the best reception direction, decodes SIB1, and performs a directional LBT procedure. The UE transmits one or more MSGs 1 having an index of the best reception direction. The gNB or M-TRP performs a directional LBT procedure and transmits one or more MSGs 2 in an idle channel direction. The UE receives one or more MSGs 2 with UL grant assignments comprising multiple directions. The UE performs a directed LBT procedure and sends an MSG3 RRC request for dual communication on a single TRP or M-TRP or a subset of idle channel directions.

Fig. 20 shows a block diagram of an embodiment processing system 2000, which may be installed in a host device, for performing the methods described herein. As shown, the processing system 2000 includes a processor 2004, a memory 2006, and interfaces 2010-2014, which may or may not be arranged as shown in fig. 20. The processor 2004 may be any component or collection of components suitable for performing computing and/or other processing related tasks, and the memory 2006 may be any component or collection of components suitable for storing programs and/or instructions for execution by the processor 2004. In one embodiment, memory 2006 includes a non-transitory computer readable medium. The interfaces 2010, 2012, 2014 may be any component or collection of components that allow the processing system 2000 to communicate with other devices/components and/or users. For example, one or more of the interfaces 2010, 2012, 2014 may be adapted to communicate data, control or management messages from the processor 2004 to applications installed on the host device and/or remote device. As another example, one or more of the interfaces 2010, 2012, 2014 may be adapted to allow a user or user device (e.g., personal computer (personal computer, PC), etc.) to interact/communicate with the processing system 2000. The processing system 2000 may include additional components not shown in fig. 20, such as long term memory (e.g., non-volatile memory, etc.).

In some embodiments, the processing system 2000 is included in a network device that accesses or is otherwise part of a telecommunications network. In one example, the processing system 2000 is located in a network side device in a wireless or wireline telecommunication network, such as a base station, a relay station, a scheduler, a controller, a gateway, a router, an application server, or any other device in a telecommunication network. In other embodiments, the processing system 2000 is located in a user side device that accesses a wireless or wireline telecommunications network, such as a mobile station, a User Equipment (UE), a personal computer (personal computer, PC), a tablet, a wearable communication device (e.g., a smart watch, etc.), or any other device suitable for accessing a telecommunications network.

In some embodiments, one or more of the interfaces 2010, 2012, 2014 connect the processing system 2000 to a transceiver adapted to send and receive signaling over a telecommunications network. Fig. 21 shows a block diagram of a transceiver 2100 suitable for transmitting and receiving signaling over a telecommunications network. The transceiver 2100 may be installed in a host device. As shown, the transceiver 2100 includes a network-side interface 2102, a coupler 2104, a transmitter 2106, a receiver 2108, a signal processor 2110, and a device-side interface 2112. The network-side interface 2102 may include any component or collection of components suitable for sending or receiving signaling over a wireless or wireline telecommunications network. Coupler 2104 may comprise any component or collection of components suitable for facilitating bi-directional communication over network-side interface 2102. The transmitter 2106 may comprise any component or collection of components (e.g., an up-converter, a power amplifier, etc.) adapted to convert a baseband signal to a modulated carrier signal suitable for transmission through the network-side interface 2102. The receiver 2108 may include any component or collection of components (e.g., a down converter, low noise amplifier, etc.) suitable for converting a carrier signal received through the network-side interface 2102 to a baseband signal. The signal processor 2110 may comprise any component or collection of components adapted to convert baseband signals to data signals suitable for communication through the device-side interface 2112 or to convert data signals suitable for communication through the device-side interface 2112 to baseband signals. The device-side interface 2112 may include any component or collection of components suitable for communicating data signals between the signal processor 2110 and components within a host device (e.g., processing system 2000, local area network (local area network, LAN) port, etc.).

The transceiver 2100 may transmit and receive signaling over any type of communication medium. In some embodiments, the transceiver 2100 transmits and receives signaling over a wireless medium. For example, the transceiver 2100 may be a wireless transceiver adapted to communicate in accordance with a wireless telecommunications protocol such as a cellular protocol (e.g., long-term evolution (LTE), etc.), a wireless local area network (wireless local area network, WLAN) protocol (e.g., wi-Fi, etc.), or any other type of wireless protocol (e.g., bluetooth, near field communication (near field communication, NFC), etc.). In such an embodiment, the network-side interface 2102 includes one or more antenna/radiating elements. For example, the network-side interface 2102 may include a single antenna, multiple independent antennas, or a multi-antenna array configured for multi-layer communications, such as single-input-multiple-output (single input multiple output, SIMO), multiple-input-single-output (multiple input single output, MISO), multiple-input-multiple-output (multiple input multiple output, MIMO), and so forth. In other embodiments, the transceiver 2100 transmits and receives signaling over a wired medium such as a twisted pair cable, coaxial cable, fiber optic cable, and the like. The particular processing system and/or transceiver may utilize all of the components shown, or only a subset of these components, and the level of integration may vary from device to device.

It should be understood that one or more steps in the example methods provided herein may be performed by corresponding units or modules. For example, the signal may be transmitted by a transmitting unit or a transmitting module. The signal may be received by a receiving unit or a receiving module. The signals may be processed by a processing unit or processing module. The corresponding units/modules may be hardware, software or a combination thereof. For example, one or more of the units/modules may be an integrated circuit, such as a field programmable gate array (field programmable gate array, FPGA) or an application-specific integrated circuit (ASIC).

Although the present specification has been described in detail, it should be understood that various changes, substitutions and alterations can be made hereto without departing from the spirit and scope of the disclosure as defined by the appended claims. Furthermore, the scope of the present disclosure is not intended to be limited to the particular embodiments described herein, as one of ordinary skill in the art will readily appreciate from the present disclosure, processes, machines, manufacture, compositions of matter, means, methods, or steps (including those presently existing or later to be developed) that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.

While this disclosure has been described with reference to illustrative embodiments, this description is not intended to be construed in a limiting sense. Various modifications and combinations of the illustrative embodiments, as well as other embodiments of the disclosure, will be apparent to persons skilled in the art upon reference to the description. Accordingly, the appended claims are intended to cover any such modifications or embodiments.

Claims (40)

1. A method for operating a User Equipment (UE), the method comprising:

decoding, by a User Equipment (UE), at least one of a Master Information Block (MIB) or a System Information Block (SIB) received from a base station;

determining, by the UE, that a Discovery Burst Transmission Window (DBTW) is enabled based at least on the decoded MIB or SIB;

decoding, by the UE, the DBTW parameters; and

a Random Access Channel (RACH) procedure is performed by the UE according to the decoded DBTW parameters.

2. The method as recited in claim 1, further comprising:

determining, by the UE, that no DBTW parameter is provided in response to the DBTW being enabled; and

in response to determining that no DBTW parameters are provided, RACH procedures are performed by the UE according to default DBTW parameters.

3. The method as recited in claim 1, further comprising:

Determining, by the UE, that a DBTW has a signal quality report; and

and reporting a synchronization signal physical broadcast channel/channel state information reference signal (SSB/CSI-RS) quality by the UE.

4. The method of claim 1, wherein the UE performs the RACH procedure according to no DBTW in response to determining that DBTW is not enabled.

5. A method, comprising:

decoding, by a User Equipment (UE), at least one of a Master Information Block (MIB) or a System Information Block (SIB) received from a base station;

determining, by the UE, that a Listen Before Talk (LBT) configuration is a default LBT cell configuration based at least on the decoded MIB or SIB; and

a message is sent by the UE using a directional LBT procedure in response to determining that the LBT configuration is a default LBT cell configuration.

6. The method as recited in claim 5, further comprising:

determining, by the UE, that the LBT configuration is not a default LBT cell configuration; and

a message is sent by the UE using a directed LBT procedure based at least on the decoded MIB or SIB.

7. The method of claim 5, wherein the message is sent by the UE without performing an LBT procedure.

8. The method as recited in claim 5, further comprising:

Receiving, by the UE, a message from the base station;

detecting, by the UE, a change in LBT; and

a second message is sent by the UE using a directed LBT procedure according to the changed LBT.

9. The method as recited in claim 8, further comprising:

receiving, by the UE, a message from the base station;

determining, by the UE, that LBT has not changed; and

a second message is sent by the UE using a directed LBT procedure based at least on the decoded MIB or SIB.

10. A method, comprising:

decoding, by a User Equipment (UE), at least one of a Master Information Block (MIB) or a System Information Block (SIB) received from a base station;

determining, by the UE, that a Listen Before Talk (LBT) configuration is a default LBT configuration based at least on the decoded MIB or SIB; and

in response to determining that the LBT configuration is a default LBT configuration, a message is sent by the UE using a directional LBT procedure.

11. The method as recited in claim 10, further comprising:

determining, by the UE, that the LBT configuration is not a default LBT configuration; and

a message is sent by the UE using a directed LBT procedure based at least on the decoded MIB or SIB.

12. The method as recited in claim 10, further comprising:

Determining, by the UE, that the LBT configuration is not a default LBT configuration; and

a message is sent by the UE without using any LBT procedure.

13. The method as recited in claim 10, further comprising:

receiving, by the UE, a message from the base station;

determining, by the UE, that the message LBT is a short signal; and

and sending, by the UE, a third message according to the back-off LBT in response to a timer timeout of the short signal.

14. The method as recited in claim 13, further comprising:

determining, by the UE, that the message LBT is not a short signal; and

and sending a third message by the UE according to the LBT configuration.

15. The method as recited in claim 10, further comprising:

receiving, by the UE, a message from the base station;

determining, by the UE, that the message LBT is a short signal; and

in response to determining that the timer for the short signal has not expired, a third message is sent by the UE without any LBT.

16. A method, comprising:

identifying, by a User Equipment (UE), a plurality of synchronization signal/physical broadcast channel (SS/PBCH) and channel state information reference signal (CSI-RS) directions according to multi-directional initial access enablement;

Performing, by the UE, a Listen Before Talk (LBT) procedure in a plurality of directions; and

a first message is transmitted by the UE in the plurality of directions, wherein each preamble in the first message corresponds to at least an SS/PBCH block (SSB) or CSI-RS.

17. The method as recited in claim 16, further comprising:

receiving, by the UE, a plurality of second messages from a base station in response to the transmission of the first message;

performing, by the UE, a directed LBT procedure in response to receiving the plurality of second messages; and

one or more third messages are sent by the UE, wherein the UE identifies itself as the only sender of the first message.

18. The method as recited in claim 17, further comprising:

receiving, by the UE, one or more fourth messages from the base station in response to the sending of the one or more third messages; and

a hybrid automatic repeat request/acknowledgement (HARQ/ACK) is sent by the UE to the base station, the HARQ/ACK indicating a mapping of a fourth message successfully received by the UE.

19. A User Equipment (UE), comprising:

a non-transitory memory including instructions; and

One or more processors in communication with the memory, the one or more processors executing the instructions to:

decoding at least one of a Master Information Block (MIB) or a System Information Block (SIB) received from a base station;

determining that a Discovery Burst Transmission Window (DBTW) is enabled based at least on the decoded MIB or SIB;

decoding the DBTW parameters; and

a Random Access Channel (RACH) procedure is performed according to the decoded DBTW parameters.

20. The UE of claim 19, wherein the one or more processors are further to execute the instructions to:

determining that no DBTW parameter is provided in response to the DBTW being enabled; and

in response to determining that no DBTW parameters are provided, a RACH procedure is performed according to default DBTW parameters.

21. The UE of claim 19, wherein the one or more processors are further to execute the instructions to:

determining that the DBTW has signal quality reporting; and

and reporting the quality of a synchronous signal physical broadcast channel/channel state information reference signal (SSB/CSI-RS).

22. The UE of claim 19, wherein the UE performs the RACH procedure according to no DBTW in response to determining that DBTW is not enabled.

23. A User Equipment (UE), comprising:

a non-transitory memory including instructions; and

one or more processors in communication with the memory, the one or more processors executing the instructions to:

decoding at least one of a Master Information Block (MIB) or a System Information Block (SIB) received from a base station;

determining that a Listen Before Talk (LBT) configuration is a default LBT cell configuration based at least on the decoded MIB or SIB; and

in response to determining that the LBT configuration is a default LBT cell configuration, a message is sent using a directional LBT procedure.

24. The UE of claim 23, wherein the one or more processors are further to execute the instructions to:

determining that the LBT configuration is not a default LBT cell configuration; and

a message is sent using a directed LBT procedure based at least on the decoded MIB or SIB.

25. The UE of claim 23, wherein the UE transmits the message without performing an LBT procedure.

26. The UE of claim 23, wherein the one or more processors are further to execute the instructions to:

Receiving a message from the base station;

detecting a change in LBT; and

the second message is sent using a directed LBT procedure according to the changed LBT.

27. The UE of claim 26, wherein the one or more processors are further to execute the instructions to:

receiving a message from the base station;

determining that LBT has not changed; and

a second message is sent using a directed LBT procedure based at least on the decoded MIB or SIB.

28. A User Equipment (UE), comprising:

a non-transitory memory including instructions; and

one or more processors in communication with the memory, the one or more processors executing the instructions to:

decoding at least one of a Master Information Block (MIB) or a System Information Block (SIB) received from a base station;

determining that a Listen Before Talk (LBT) configuration is a default LBT configuration based at least on the decoded MIB or SIB; and

in response to determining that the LBT configuration is the default LBT configuration, a message is sent using a directional LBT procedure.

29. The UE of claim 28, wherein the one or more processors are further to execute the instructions to:

Determining that the LBT configuration is not a default LBT configuration; and

a message is sent using a directed LBT procedure based at least on the decoded MIB or SIB.

30. The UE of claim 28, wherein the one or more processors are further to execute the instructions to:

determining that the LBT configuration is not a default LBT configuration; and

the message is sent without using any LBT procedure.

31. The UE of claim 28, wherein the one or more processors are further to execute the instructions to:

receiving a message from the base station;

determining that the message LBT is a short signal; and

and sending a third message according to the back-off LBT in response to the timer timeout of the short signal.

32. The UE of claim 31, wherein the one or more processors are further to execute the instructions to:

determining that the message LBT is not a short signal; and

and sending a third message according to the LBT configuration.

33. The UE of claim 28, wherein the one or more processors are further to execute the instructions to:

receiving a message from the base station;

determining that the message LBT is a short signal; and

In response to determining that the timer for the short signal has not timed out, the third message is sent without any LBT.

34. A User Equipment (UE), comprising:

a non-transitory memory including instructions; and

one or more processors in communication with the memory, the one or more processors executing the instructions to:

identifying a plurality of synchronization signal/physical broadcast channel (SS/PBCH) and channel state information reference signal (CSI-RS) directions in accordance with the multi-directional initial access being enabled;

performing a Listen Before Talk (LBT) procedure in a plurality of directions; and

a first message is sent in the plurality of directions, wherein each preamble in the first message corresponds to at least an SS/PBCH block (SSB) or CSI-RS.

35. The UE of claim 34, wherein the one or more processors are further to execute the instructions to:

receiving a plurality of second messages from a base station in response to the transmission of the first messages;

in response to receiving the plurality of second messages, performing a directed LBT procedure; and

one or more third messages are sent, wherein the UE identifies itself as the only sender of the first message.

36. The UE of claim 35, wherein the one or more processors are further to execute the instructions to:

receiving one or more fourth messages from the base station in response to the sending of the one or more third messages; and

a hybrid automatic repeat request/acknowledgement (HARQ/ACK) is sent to the base station, the HARQ/ACK indicating a mapping of a fourth message successfully received by the UE.

37. A method, comprising:

receiving, by a Transmission Reception Point (TRP), a plurality of MSGs 1;

performing, by the TRP, a Listen Before Talk (LBT) procedure in a plurality of directions according to the received plurality of MSGs 1, the LBT procedure indicating a first set of successful LBT directions;

transmitting, by the TRP, one or more MSGs 2 according to the first set of successful LBT directions;

receiving, by the TRP, one or more MSGs 3;

determining, by the TRP, whether the one or more MSGs 3 map to the same UE;

in response to determining that the one or more MSGs 3 are not mapped to the same UE, performing, by the TRP, an LBT procedure according to directions associated with the plurality of UEs, the LBT procedure indicating a second set of successful LBT directions; and

one or more MSGs 4 are transmitted by the TRP to a plurality of UEs according to the second set of successful LBT directions.

38. The method as recited in claim 37, further comprising:

in response to determining that the one or more MSGs 3 map to a single UE, merging, by the TRP, identities of the one or more MSGs 3 to the single UE;

performing, by the TRP, an LBT procedure according to a direction associated with the single UE, the LBT procedure indicating a third set of successful LBT directions;

transmitting, by the TRP, MSG4 to the single UE according to the third set of successful LBT directions; and

a hybrid automatic repeat request/acknowledgement (HARQ/ACK) is received by the TRP, the HARQ/ACK comprising a mapping of successful MSG 4.

39. A transmission-reception point (TRP), comprising:

a non-transitory memory including instructions; and

one or more processors in communication with the memory, the one or more processors executing the instructions to:

receiving a plurality of MSGs 1;

performing a Listen Before Talk (LBT) procedure in a plurality of directions according to the received plurality of MSGs 1, the LBT procedure indicating a first set of successful LBT directions;

transmitting one or more MSG2 according to the first set of successful LBT directions;

receiving one or more MSGs 3;

determining whether the one or more MSGs 3 map to the same UE;

In response to determining that the one or more MSGs 3 are not mapped to the same UE, performing an LBT procedure according to directions associated with the plurality of UEs, the LBT procedure indicating a second set of successful LBT directions; and

and sending one or more MSG4 to a plurality of UEs according to the second group of successful LBT directions.

40. The TRP of claim 39, wherein the one or more processors are further to execute the instructions to:

in response to determining that the one or more MSGs 3 map to a single UE, merging identities of the one or more MSGs 3 to the single UE;

performing an LBT procedure according to a direction associated with the single UE, the LBT procedure indicating a third set of successful LBT directions;

transmitting MSG4 to the single UE according to the third set of successful LBT directions; and

a hybrid automatic repeat request/acknowledgement (HARQ/ACK) is received, the HARQ/ACK comprising a mapping of successful MSG4.